Air Toxics: Air Risk Assessment

The National-Scale Air Toxics Assessment (NATA), based on 1996 emissions data, looked at 33 air pollutants in order to identify the pollutants that are of greatest concern to human heath and the environment. The results from NATA will be used to set priorities for the collection of additional air toxics data.

EPA is currently developing a reference library for conducting air toxics analyses at the facility and community-scale. This effort will result in a three volume library that provides information on the fundamental principles of risk-based assessment for air toxics and how to apply those principles in different settings as well as strategies for reducing risk at the local level. Volumes 1 and 2 are completed and are available. Volume 3 is currently being developed and is expected to be available by the end of the year.

The Human Exposure Model (HEM) is a computer-modeling program used for performing risk assessment for major point sources. The HEM addresses the inhalation pathway of exposure and is designed to predict risks associated with emitted chemicals in the ambient air.

The Integrated Risk Information System (IRIS) is a database of human health effects that may result from exposure to various substances found in the environment. IRIS was initially developed for EPA staff in response to a growing demand for consistent information on chemical substances for use in risk assessments, decision-making and regulatory activities.